"Vodafone is aware that a law firm which is known for promoting class actions has repeated longstanding plans to proceed with action against us," the company said in a statement.

"That firm has not contacted Vodafone directly about this since it first threatened action in 2010, nor has it sought to discuss the claims of any customers it represents in the class action with Vodafone.

"Vodafone has not been provided with any details of the class action at this stage and is therefore not able to comment on the claims which might be made."

The legal move comes more than a year after Vodafone said it was working hard to improve its service.

This followed a damning report outlining more than 12,000 complaints ranging from patchy network coverage to poor customer service.

Last month, Vodafone began winding up its Crazy John's mobile phones and accessories brand, saying as many as 300 jobs are at risk as the company decides how to deploy staff.